OP THE PLANET NEPTUNE. 429 



planet; as well as the difficulties interposed in consequence of its 

 remote distance from our earth, must necessarily render the absolute 

 determination of all its peculiar phenomena a work of time. Mean- 

 while it may be permitted us to reason that, if Neptune is self-lumi- 

 nous, this condition may enable it, with its solitary satellite, to pos- 

 sess a sufficiency of light for the existence and enjoyment of life by 

 creatures of a higher organization than some feel disposed to accord 

 to it, should life indeed exist upon it at present. 



With regard to the temperature of these remote bodies which 

 must necessarily be dependent upon a variety of considerations, I 

 cannot but think some allowance should be made for the greater 

 amount of internal heat which may possibly be a condition of the 

 superior planets ; for if, as some are disposed to consider, the Solar 

 System had a common origin, and the planets originally were in an 

 incandescent state, then under such circumstances the larger bodies 

 would take longer to cool down than the smaller ones — and if any 

 degree of probability is to be attached to such speculations, our 

 friends on the confines of the system, (if such there be) may still be 

 warmer than we give them credit for. 



I am not, however, going to inflict on the members of the Institute 

 any dissertation on the plurality or non-plurality of worlds, which 

 subject has assuredly been sufficiently discussed of late years, 

 leaving us all much of the same opinion still, although some of us 

 may have been convinced against our will. But if any feel disposed 

 to view this vexed question under a new aspect, and see much that is 

 valuable, original and interesting, presented in a very condensed form, 

 I strongly recommend them to peruse a little work called " The 

 Chemistry of the Stars," written by Dr. George Wilson, the recent- 

 ly appointed Professor of Technology, at Edinburgh ; and I think 

 they will come to the conclusion, that it contains as much as need be 

 said upon the subject to convince us all, that it is not probable there 

 is any planet in the Solar System adapted for the residence of beings 

 constituted precisely as we are. 



I may add that when Neptune was discovered by Dr. Galle, it ap- 

 peared as a star of the 8th magnitude ; its apparent diameter is 

 about 2"- 8 when in opposition, that of Uranus in the same position 

 is about 4". If we had a first class telescope attached to this In- 

 stitute, or to one of the Universities, we might have opportunities 

 of satisfying ourselves by personal inspection of the comparative 

 light given forth by these two planets. The acquisition of such an 

 instrument is, I regret to say, still a consummation devoutly to be 

 wished. 



